Passive network tap with digital signal processing for separating signals

ABSTRACT

A passive full-duplex bidirectional ZPL tap includes first and second network ports and tap ports. A signal separator is configured to receive a data stream from at least one of the first or second network ports and pass through the data stream and configured to obtain a first signal portion comprising at least the first signal component and obtain a second signal portion comprising at least the second signal component. A DSP stage is configured to substantially remove any second data component from the first signal portion and to substantially remove any first data component from the second signal portion. A first receive only Phy is configured to receive the first signal portion and provide the first signal portion to the first tap port and a second receive only Phy is configured to receive the second signal portion and provide the second signal portion to the second tap port.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/560,341, filed Nov. 15, 2006.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/737,240, filed Nov. 15,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/739,879, filed Nov. 23,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/739,513, filed Nov. 23,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/739,649, filed Nov. 23,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/739,512, filed Nov. 23,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/739,648, filed Nov. 23,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/753,348, filed Dec. 22,2005.

U.S. patent application Ser. No. 11/560,341 claims the benefit of andpriority to U.S. Provisional Application No. 60/771,932, filed Feb. 9,2006.

All of the above referenced applications are incorporated herein byreference in their entirety.

BACKGROUND

The dependence upon the use of data networks to transmit and receivedata at high data rates has led to a corresponding interest in theability to perform real-time monitoring and analysis of that data, ornetwork traffic, so that duplication of data as well as performance ofthe network can be evaluated, and problems identified and resolved. Suchdata monitoring and analysis necessitates the ability to access thenetwork data stream without disrupting data transmission and theoperation of the network.

To this end, monitoring systems utilizing network taps are employedwhich are configured so that network data can be captured for analysiswithout interrupting operation of the network. In general, such usevarious mechanisms to access network data. For example, some tapsinclude a buffering mechanism that enables the capture of network data.In other cases, network taps are able to copy selected portions of thedata stream, and then provide the copied portion of the data stream to anetwork analyzer or other device for evaluation.

Referring to FIG. 1, a conventional copper-based Ethernet monitoringsystem 100 is illustrated. For example, an Ethernet device 101 is shownas being in communication with an Ethernet device 102 using standardCat5 network cable. As per the Gigabit Ethernet standard, thecommunication on the twisted pair cable is bidirectional as is depictedby arrows 110 and 111.

Also illustrated is a tap 120 which is situated in the communicationpath between Ethernet devices 101 and 102. Tap 120 is used to access thedata signals for monitoring. The tap includes relays 121 and 122 thatcan direct the signal path flow.

Further included in system 100 are four Physical Interface Devices(Phys) 131-134. These Phys may be individuals or contained in two dualor one 130 quad IC package as shown. The Phys provide the physicalconnection between the copper Cat5 cable and the communication network.

In operation, when it is desirable to monitor the data flow betweenEthernet devices 101 and 102, the relays 121 and 122 of tap 120 areenergized causing the flow of information between Ethernet devices 101and 102 to be redirected to Phys 132 and 133. For example, energizedrelay 121 causes the data from device A 101, referred to as A data, toflow to Phy 132. Phy 132 sends the A data signal to Phy 131, where it isprovided to monitor A for monitoring and to Phy 133, which provides theA data to energized relay 122 and device B 102. In like manner,energized relay 122 causes data from device B 102, referred to as Bdata, to flow to Phy 133. Phy 133 sends the B data signal to Phy 134,where it is provided to monitor B for monitoring and to Phy 132, whichprovides the B data to energized relay 121 and device A 101.Accordingly, system 100, utilizing a tap 120 with a combination ofrelays 121, 122 and quad Phy 130, is able to monitor the communicationbetween Ethernet devices A 101 and B 102 while still allowing thedevices to communicate bi-directionally.

While system 100 has generally proven to be useful in enabling themonitoring and analysis of network traffic, significant problems remainwith this conventional system. One problem of particular concern is thatnetwork tap 120 is often susceptible to a power loss or other faultconditions. For example, the external power supply to the network tap isa significant failure point in the system. Unfortunately, disconnectionof such external power supplies is a relatively common occurrence. Inmany cases, disconnection of the external power supply to the networktap occurs because the network tap and power supply are located in aplace where personnel may inadvertently, or mistakenly, unplug the powersupply. These challenges are only magnified where multiple network tapsare implemented in the communication network or other system.

Any loss of power or other fault typically causes relays 121 and 122 toclose. Consequently, any A data and B data that would have passedthrough the relays 121 and 122 during the switching operation is lost.Also, any data that is in tap 120 and the quad Phy 130 when power isinterrupted is also lost. In addition, Ethernet devices 101 and 102 mustreconfigure themselves to properly communicate, which also disruptsnetwork data flow. In view of the high data speeds employed in manynetworks, even a very short term interruption in power to the networktap 120 will seriously compromise the integrity of the data stream, sothat even if the network is otherwise in operational condition, aninterruption of power to the network tap and the resulting loss of datacan severely impair operation of the network. This lack of faulttolerance in many high speed data communication network taps is a majorconcern that remains largely unaddressed.

BRIEF SUMMARY

The principles of the present invention relate to a passive full-duplexbidirectional Zero Packet Loss (ZPL) network tap coupled to thecommunication path of a copper-based communications network includingfirst and second devices. The first and second devices communicate byuse of a full-duplex bidirectional data stream including first andsecond data components.

The passive fall-duplex bidirectional ZPL network tap includes first andsecond network ports configured to operably connect with firstcommunication cables, the first communication cables configured to carrythe fall-duplex bidirectional data stream to and from the network tap.First and second tap ports configured to operably connect with secondcommunication cables may also be included.

The passive full-duplex bidirectional ZPL network tap further includes asignal separator having a first node connected to the first network portand a second node connected to the second network port. The signalseparator is configured to pass through the fall-duplex bidirectionaldata stream from the first network port to the second network port andfrom the second network port to the first network port. The signalseparator is further configured to obtain a first signal portioncomprising at least the first signal component and a second signalportion comprising at least the second signal component.

The passive full-duplex bidirectional ZPL network tap also includes oneor more Digital Signal Processing (DSP) stages configured to receive thefirst and second signal portions and to substantially remove any seconddata component from the first signal portion and to remove any firstdata component from the second signal portion.

The passive full-duplex bidirectional ZPL network tap also includes afirst receive only physical interface device (Phy) configured to receivethe first signal portion from the signal separator and provide the firstsignal portion to the first tap port and a second receive only Phyconfigured to receive the second signal portion from the signalseparator and provide the second signal portion to the second tap port.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

Additional features and advantages of the invention will be set forth inthe description that follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Thefeatures and advantages of the invention may be realized and obtained bymeans of the instruments and combinations particularly pointed out inthe appended claims. These and other features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 illustrates a conventional copper based Ethernet monitoringsystem;

FIG. 2 illustrates a communications network including passivefull-duplex bidirectional ZPL network tap array;

FIG. 3 illustrates a passive full-duplex bidirectional ZPL network tap;

FIG. 4 illustrates internal and other features of the passivefull-duplex bidirectional ZPL network tap;

FIGS. 5A-5C illustrate embodiments of signal separators withbidirectional couplers;

FIGS. 6A-6D illustrate examples of actual signal separation achievableby a signal separator by itself or in combination with a signalseparation stage;

FIG. 7 illustrates a plurality of passive full-duplex bidirectional ZPLnetwork taps housed in a chassis of a tap array;

FIG. 8 illustrates a passive full-duplex bidirectional ZPLtap/aggregator;

FIG. 9 illustrates a method for separating a first and a second signalcomponent from a first data stream used in full-duplex bidirectionalcommunication between two devices according to principles of the presentinvention;

FIG. 10 illustrates an environment and process flow that may beimplemented to perform an operation to extract the a first signalcomponent from a data stream comprising the first component and a secondcomponent that is less than the first component according to principlesof the present invention;

FIG. 11 illustrates a method for configuring and using a listen orreceive only Phy according to principles of the present invention; and

FIG. 12 illustrates an equipment rack in which multiple sub-chassis arecombined together.

DETAILED DESCRIPTION

As disclosed in this description, and in the accompanying drawings whichare also included as part of the present disclosure, embodiments of thepresent invention are concerned with passive full-duplex bidirectionalZero Packet Loss (ZPL) network taps (also hereinafter referred to as a“ZPL” tap) and associated devices, hardware and software in connectionwith copper-based Ethernet networks and other communications networks.Among other things, the passive full-duplex bidirectional ZPL networktap eliminates potential network data loss due to power loss or otherfault in the ZPL tap, which contributes to a relative improvement in thereliability and operation of the network.

One example of such a passive full-duplex bidirectional ZPL network tapis configured for use with communications networks wherein two networkdevices communicate using bidirectional full-duplex data signals, suchas, but not limited to, point to point Ethernet networks employing datarates, including, but not limited to, 10/100/1000 Mbit/sec., or evenfaster rates. More generally however, embodiments of the invention aresuited for operation with any network where data is carried over thenetwork lines. Accordingly, the scope of the invention should not beconstrued to be limited to any specific network type or data rate.

Further, it should be noted that unlike conventional taps, which userelays with physical switches as described previously, exemplary passivefull-duplex bidirectional ZPL network taps of the invention do notinclude any active components positioned in-line with a network cablethat could cause data packet loss or otherwise cause users on either endof the network link to be aware of the fact that data is being accessedby a ZPL tap. In other words, regardless of power loss or other fault tothe passive full-duplex bidirectional ZPL network tap, there is no lossof communication between devices communicating over the network.

Additionally, some embodiments of the passive full-duplex bidirectionalZPL network tap are employed in a stand-alone configuration where thepassive full-duplex bidirectional ZPL network tap obtains data from thenetwork and then passes the data to a remote, or external, device suchas an analyzer, bit error rate tester (“BERT”) and/or other device. Inyet other implementations however, the passive full-duplex bidirectionalZPL network tap is incorporated into another device, such as a portableanalyzer for example. Thus, embodiments of the invention embraceportable analyzers and other devices that incorporate a passivefull-duplex bidirectional ZPL network tap. In still further embodiments,a group of passive full-duplex bidirectional ZPL network taps areincorporated together into a bank, block or similar configuration sothat the network data stream can be tapped and directed to multipledevices by way of respective ZPL taps. Such banks or blocks can beconfigured in serial or parallel fashion.

Of course, the scope of the invention is not limited to datacommunications network applications. By way of example, embodiments ofthe passive full-duplex bidirectional ZPL network tap are suitable foruse in Voice Over Internet Protocol (“Voice Over IP”) systems andapplications. Yet other embodiments are employed in monitoring telephonelines. As mentioned, exemplary bidirectional passive full-duplexbidirectional ZPL network taps are configured such that users on eitherend of the network link are unaware of the fact that data is beingaccessed by a tap. This feature is particularly useful for governmentalagencies or other entities that are authorized to access network datafor the purposes of monitoring and surveillance of communications.

Embodiments of the passive full-duplex bidirectional ZPL network tapinclude a variety of components which enable the network tap toimplement network data stream tap functionality. More particular detailsconcerning such components and their functionalities and operations areprovided below in connection with the discussion of FIG. 2. An examplecopper-based Ethernet monitoring system in which a passive full-duplexbidirectional ZPL network tap may be employed will first be described,followed by aspects of an example passive full-duplex bidirectional ZPLnetwork tap. Note that the principles of the present invention are notlimited to any specific environment.

I. Example Copper-Based Ethernet Monitoring System Employing a ZPL Tap

Reference is now made to FIG. 2, which depicts one example of anoperating environment in which passive full-duplex bidirectional ZPLnetwork tap can be utilized, in accordance with one example embodimentof the present invention. Alternatively, the environment depicted inFIG. 2 can also represent an environment in which a passive full-duplexbidirectional ZPL network Tap and Aggregator of embodiments of thepresent invention can be included, as discussed further below.

In particular, FIG. 2 shows a block diagram of a communications network,or computer network 200, including a passive full-duplex bidirectionalZPL network tap array (“ZPL tap array”), generally designated at 250, inaccordance with one embodiment of the present invention. Althoughcomputer network 200 was selected to illustrate the present invention,any computer network topology can be used with the present invention,including but not limited to various combinations of network servers,switches, routers, hubs and various end user computers/terminals.Indeed, various modifications to both the passive full-duplexbidirectional ZPL network tap array and its operating environment can berealized while still residing within the scope of the present claimedinvention. Hereinafter, individual elements forming a group of likeelements may also be referred to by a letter designation.

In greater detail, the computer network 200, in a selected networksegment 201, generally includes a network server 202, a network switch204 (e.g., a router), desktop computers 206 a-c, and the passivefull-duplex bidirectional ZPL network tap array 250. The ZPL tap array250 includes a chassis 252 that contains a plurality n of bidirectionalfall-duplex ZPL tap devices 300.

The network server 202, the desktop computers 206 b, c and the passivefull-duplex bidirectional ZPL network tap 300 are coupled directly tothe network switch 204. The passive full-duplex bidirectional ZPLnetwork tap 300 is coupled between the network switch 204 and thedesktop computer 206 a via cables 208 a, b. The passive full-duplexbidirectional ZPL network tap 300 is further coupled to a monitoringdevice 210 via cables 212 a, b. For Gigabit Ethernet, the cables 208 and212 are typically four-pair Cat5 twisted-pair cables, but the passivefull-duplex bidirectional ZPL network tap 300 can also work with10BASE-T and 100BASE-T Ethernet systems, which typically use Category 3(Cat3) cables, or with other suitable transmission lines. The passivefull-duplex bidirectional ZPL network tap 300 can be programmed tooperate with multiple Ethernet speeds and cables using an onboardmicroprocessor, discussed further below, or by setting jumpers and/orswitches in the passive full-duplex bidirectional ZPL network tap.Similarly, the other n passive full-duplex bidirectional ZPL network tapdevices 300 are operably coupled to corresponding monitoring devices,such as the monitoring devices 220 and 230 shown in FIG. 2, and theiroperation with regard to their respective monitoring devices is asdescribed below with respect to the ZPL tap 300 and monitoring device210. In one embodiment each passive full-duplex bidirectional ZPLnetwork tap device is coupled to only one monitoring device; in otherembodiments, one monitoring device is coupled to more than one ZPL tapdevice. The term “monitoring device” as used herein is understood toinclude a network analyzer or other diagnostic equipment, intrusiondetection system, or any other device used to monitor and/or analyze theoperational status or data content of a computer network segment.

In a typical network session, the desktop computer 206 a requests fromthe network server 202 a file containing information needed by anapplication program executing on the desktop computer 206 a. The desktopcomputer 206 a issues a request to the network server 202, whichpropagates through the passive fall-duplex bidirectional ZPL network tap300 to the network switch 204 via cables 208 a, b. The network switch204 reviews the destination address of the request and routes it to thenetwork server 202 via cable 208 c. The network server 202 responds withthe requested data. The requested data is sent from the network server202 to the network switch 204 via cable 208 c. The network switch 204routes the data to the desktop computer 206 a via the passivefull-duplex bidirectional ZPL network tap 300 and cables 208 a, b.

To view the request made by the desktop computer 206 a and response madeby the network server 202, the passive full-duplex bidirectional ZPLnetwork tap 300 is physically connected between the network switch 204and desktop computer 206 a. Full-duplex data flows simultaneously inboth directions over the cables 208. Examples of bidirectionalfull-duplex signals are point to point Gigabit Ethernet data over thecable 208. In the present embodiment, the passive full-duplexbidirectional ZPL network tap 300 provides an independent copy, via thecables 212 a, b, of the data flowing in either direction to themonitoring device 210. For example, a request from the desktop computer206 a travels through the network switch 204 to network server 202, andis tapped and sent out a tap port of the passive full-duplexbidirectional ZPL network tap 300 over cable 212 a to the monitoringdevice 210. Likewise, data returning from the network server 202 istapped and sent out another monitoring port of the passive full-duplexbidirectional ZPL network tap 300 over cable 212 b to the monitoringdevice 210.

For purposes of discussion, selected components of the computer network200 as included in the network segment 201 were discussed above. Thecomputer network 200 can be thought of as having a plurality of suchsegments, such as network segments 213 and 223 shown in FIG. 2. In moredetail, the network segment 213 includes a switch 214 and computers 216a-c. The switch 214 is operably connected to a respective one of the npassive full-duplex bidirectional ZPL network taps 300, which in turn isoperably connected to the monitoring device 220. Similarly, the networksegment 223 includes a switch 224 and computers 226 a-c. The switch 224is operably connected to a respective one of the n ZPL taps 300, whichin turn is operably connected to the monitoring device 230. Theoperation of the passive full-duplex bidirectional ZPL network taps 300of the ZPL tap array 250 that are associated with the network segments213 and 223 are the same as that described for the passive full-duplexbidirectional ZPL network tap of the network segment 201. Furthermore,note that the network segments described above are defined only forpurposes of discussion and are merely representative of one of a varietyof possible network and component configurations with respect to the ZPLnetwork tap array 250. Note also that, for purposes of clarity, not alloperable connections between the various network components are shown orexplicitly identified.

Together with FIG. 2, reference is now made to FIG. 3, which depicts anetwork tap device in the form of one passive full-duplex bidirectionalZPL network tap 300, in accordance with one embodiment. The passivefull-duplex bidirectional ZPL network tap 300 shown in FIG. 3 is alsoreferred to herein as a 1×1 passive full-duplex bidirectional ZPLnetwork tap and corresponds to any one of the passive full-duplexbidirectional ZPL network taps grouped together in the chassis 252 ofthe ZPL tap array 250 depicted in FIG. 2 and discussed above. As such,the collection of n passive full-duplex bidirectional ZPL network taps300 in the ZPL tap array 250 can be employed to provide a non-aggregatedTapping function with respect to multiple data streams that aretransmitted through the ZPL tap array 250 during operation.

In general, the passive full-duplex bidirectional ZPL network tap 300 isa plug-in type card that can be readily inserted into and removed from achassis, such as the chassis 252 of FIG. 2. This card configuration issometimes referred to as implementing a “blade” form factor. In oneexample implementation, the blade form factor for the 1×1 passivefull-duplex bidirectional ZPL network TAP card is about 3.5 inches wideby about 1.4 inches high by about 5.5 inches deep. However, the scope ofthe invention is not limited to those exemplary dimensions.

In greater detail, the passive full-duplex bidirectional ZPL network tap300 includes a housing 352 having a front face 352A. A plurality ofports 302 and 304, to be described further below, are included on thefront face 352A for enabling connection of communication cables, such asthe cables 208 and 212 shown in FIG. 2, with the passive full-duplexbidirectional ZPL network tap. A printed circuit board 354 is alsoincluded with the ZPL tap 300 on which a plurality of electroniccomponents, some of which will be described below in connection withFIG. 4, are located. A fan 356 may be included on the printed circuitboard so as to provide cooling as needed to the electronic boardcomponents. A power supply connector 358 is also included adjacent therear portion of the passive full-duplex bidirectional ZPL network tap300. In addition, a mounting component, such as a mounting screw 360,may be included on the front face 352A to assist in coupling the passivefull-duplex bidirectional ZPL network tap 300 to the chassis 352. Notethat the locations of ports 302 and 304 in FIG. 3 and the other figuresis for illustration only as it is anticipated in some embodiments thatthe network ports 302 may be implemented above the tap ports 304.

II. Example Passive Full-Duplex Bidirectional ZPL Network Tap

Embodiments of an example passive full-duplex bidirectional ZPL networktap will now be discussed in further detail with respect to FIG. 4,which illustrates various internal and other features of the passivefall-duplex bidirectional ZPL network tap 300 of FIG. 3 in greaterdetail. Note that it is anticipated that passive full-duplexbidirectional ZPL network tap 300 may also include additional featuresand components not discussed herein such as standard line isolationtransformers.

For example, the passive full-duplex bidirectional ZPL network tap 300includes various ports for receiving and transmitting data to and fromnetwork components, as depicted in FIG. 2. Two network ports 302 a and302 b, also referred to herein as “network A” and “network B” ports, areconfigured to couple with cables 208 a and 208 b of the network 200 ofFIG. 2, thereby interlinking the passive full-duplex bidirectional ZPLnetwork tap 300 with the network. Similarly, two tap ports 304 a and 304b, also referred to herein as “tap A” and “tap B” ports, are configuredto couple with cables 212 a and 212 b (FIG. 2), thereby linking thepassive full-duplex bidirectional ZPL network tap 300 to the monitoringdevice 210. Each of the ports 302 and 304 is configured to receive anRJ-45 plug of the respective cable 208 or 212, typical of Ethernet-basednetworks, though other port/plug configurations could be alternativelyused. Thus, in the case of Cat5 cables 208 a and 208 b, four twistedpairs of each cable create eight total conductors that interconnect withterminals in the network ports A and B, thereby electrically connectingeach cable with the passive full-duplex bidirectional ZPL network tap300. As explained herein, the ports 302, 304 enable both data signalsand/or ZPL signals to enter and depart the passive full-duplexbidirectional ZPL network tap 300, as will be described further below.As noted above, the data signals received by ports 302 a and 302 b arefull duplex bidirectional signals, which will also be referred to hereinas A+B data to denote the full duplex bidirectional nature of thesignals coming from a device A and a device B coupled with passivefull-duplex bidirectional ZPL network tap 300.

Passive full-duplex bidirectional ZPL network tap 300 also includes asignal separator 310 that is operably connected to both ports 302 a and302 b. Signal separator 310 is configured to separate the A data fromthe B data received at ports 302 a and 302 b from each other and toprovide the separated data streams to other components of the passivefull-duplex bidirectional ZPL network tap 300. Signal separator 310 maybe implemented in analog or digital hardware or any combination of thetwo. In some example embodiments, signal separator 310 may beimplemented as a bidirectional coupler, dual directional coupler, or adifferential bidirectional coupler, all of which will be described inmore detail to follow. Note that all specific implementations of signalseparator 310 disclosed herein are for illustration only and should notbe used to limit the scope of the invention as signal separator 310 isnot limited by to specific implementation. Note that the componentsdiscussed herein are “operably connected” to one another when datasignals are able to pass from one component to the other. Theseconnections are indicated in FIG. 4 by the arrows drawn between thevarious components.

In some embodiments, signal separator 310 may include an amplifier 315,which may be any reasonable amplifier. In other embodiments, theamplifier 315 may be coupled to the signal separator 310 and included inanother portion of passive full-duplex bidirectional ZPL network tap300. Amplifier 315 may be configured to amplify the signals that areseparated by signal separator 310 prior to the separated signals beingsupplied to other portions of the ZPL tap 300.

As it may not be possible for signal separator 310 to fully separate theA and B full duplex data signals from each other, passive full-duplexbidirectional ZPL network tap 300 further includes a signal separationstage 320 that is operably connected to signal separator 310 and/or oneof the Phys 330-360 described below. Signal separation stage 320receives at least partially separated signals from the signal separator310 and is configured to further separate the A and B data from eachother. Signal separation stage 320 may be implemented as a separateprocess or operation, or as discrete circuit components included in thesignal separator 310. Signal separation stage 320 may also beimplemented as a part of one of the Phys 330-360. The signal separationstage or module 320 may also be included in a microprocessor 370. Insome embodiments, signal separation stage 320 may be dispersed amongseveral of the components of the passive full-duplex bidirectional ZPLnetwork tap 300. Signal separation stage 320 will be discussed in moredetail to follow.

Passive full-duplex bidirectional ZPL network tap 300 also includesPhysical Interface Device (“Phy’) Phys 330-360. These Phys may beindividual Phys, be contained in two dual packages or one quad packageas shown by dashed line 331. As illustrated, Phy 330 and Phy 340 areoperably connected to signal separator 310 and/or signal separationstage 320. Phys 330 and 340 are further operably connected to Phy 350and Phy 360 respectively. Phy 350 and Phy 360 are in turn operablyconnected to tap ports 304 a and 304 b respectively. Note that one ormore line isolation transformers (not illustrated) may be coupledbetween Phys 350 and 360 and tap ports 304 a and 304 b for performingsignal isolation functions for the respective data signal passingthrough the line isolation transformers during tap operation.

The Phys 330-360 represent integrated circuitry or functional blocksthat provide physical access to the data stream received from ports 302and 304. The Phys 330-360 are further configured to receive a datasignal and convert it to a particular data format. For instance, in oneembodiment Phys 330 and 340 receive data signals from the signalseparator 310 in a 1000BASE-T signal format, used with Cat5 coppercabling, and convert the signals to a digital data signal stream inpreparation for later use. Note that Phys 330 and 340 are configuredaccording to the principles of the present invention to be listen onlyor receive only Phys. This novel functionality will be explained in moredetail to follow.

In some embodiments, a microcontroller 370 that is programmed to monitorand control the operation of the passive full-duplex bidirectional ZPLnetwork tap 300 is also included. In general, the microcontroller 370includes various components, including integrated A/D (“Analog toDigital”) converter inputs as well as digitally programmable inputs andoutputs (“I/O”), and is programmed as desired to enable achievement ofdesired functions with respect to the operation of the ZPL network tap.By way of example, the microcontroller 370 is programmed to configurePhys 330-360 to perform the data format translation needed for properoperation of the passive full-duplex bidirectional ZPL network tap 300.Generally, the microcontroller 370 can include internal diagnosticcircuitry that enables the passive full-duplex bidirectional ZPL networktap 300 to identify and report faults in the operation of the tap and/orwith regard to operation of the computer network 200 with which the ZPLtap 300 is connected. In some embodiments, the diagnostic circuitry ofthe microcontroller 370 also provides the capability for the passivefull-duplex bidirectional ZPL network tap 300 to resolve identifiedfaults. Some embodiments of the invention include indicators, such asLED visual indicators 345 (FIG. 3), which operate in connection with thediagnostic circuitry to provide a user with information concerning theoperational status and condition of the ZPL tap 300.

Similarly, FIG. 4 shows that the passive full-duplex bidirectional ZPLnetwork tap 300 includes a temperature sensor 380, operably connected tothe microcontroller 370, for monitoring one or more temperatureconditions relating to operation of the tap. Should excessivetemperature conditions be encountered, the microcontroller 370 candirect corrective measures to be taken so as to prevent damage to thepassive full-duplex bidirectional ZPL network tap 300 or interruption ofthe data stream. The microcontroller 370 can also control operation ofany user interface, such as an LED panel.

FIG. 4 further shows the passive full-duplex bidirectional ZPL networktap 300 as including a traditional external power link 390 for plugginginto a wall outlet, for instance. As mentioned previously, passivefull-duplex bidirectional ZPL network tap 300 may also include variousother components that are not illustrated.

III. Example Signal Separators Including Differential BidirectionalCouplers

As mentioned previously, signal separator 310 may be implemented invarious forms. Referring to FIGS. 5A-5C, three different exampleembodiments of signal separator 310 are depicted as variousbidirectional couplers. Note that the example bidirectional couplers ofFIGS. 5A-5C are for illustration only and are not meant to limit thescope of the appended claims. As will be appreciated, any reasonablebidirectional coupler may be used to implement the principles of thepresent invention. The example bidirectional couplers of FIG. 5 may havethe following characteristics: 20 dB of coupling, 1 to 2 dB of insertionloss, and 20 dB of directivity. Note that these characteristics are onlyexamples of the many characteristics of a bidirectional coupler that maybe implemented according to the principles of the present invention andshould not be used to limit the scope of the appended claims. Also notethat although FIGS. 5A-5C depict a bidirectional coupler for a singletwisted pair cable, it is also contemplated that the variousbidirectional couplers of FIGS. 5A-5C may include additional couplersfor additional twisted pairs. For example, a coupler for a Cat5 cablewould have four couplers for the four twisted pairs of the Cat5 cable.

Referring to FIG. 5A, an example single bidirectional coupler 510 isdepicted as being coupled to the communication path with an Ethernetdevice 501 (A system) and an Ethernet device 502 (B system). Asmentioned previously, the Ethernet devices communicate using a fullduplex bidirectional 100 ohm differential twisted pair cable, which isdepicted in FIGS. 5A-5C as the DATA+ and DATA− lines. However, singlebidirectional coupler 510 is configured for a single ended 50 ohm line.Accordingly, impendence matching circuits 515 and 516 are implemented tomatch the 100 ohm twisted pair to the 50 ohm single ended line so thatthe A and B data can flow through the coupler 510 to the Ethernetdevices 501 and 502 respectively. As impendence matching circuits ofthis type are well known in the art, no further description isnecessary.

In operation, single bidirectional coupler 510 is configured to couple asample of the A data out of the full duplex bidirectional A+B data beingtransmitted and to also couple a sample of the B data out of the A+Bbeing transmitted. Since coupler 510 is a bidirectional coupler, coupler510 includes a couple forward (CF) and a couple reverse (CR) node thatare both used in the coupling operation. For example, the CF node isused to couple out the A data and the CR node is used to couple out theB data. However, since the A+B data is bidirectional, coupler 510 maynot be able to fully isolate the A and B data and consequently maycouple out a sampled signal that is labeled as Ab data, whichillustrates that the signal mostly comprises A data, but may have someportion of B data included. Coupler 510 may further couple out a sampledsignal that is labeled as Ba data, which illustrates that the signalmostly comprises B data, but may have some portion of A data included.The sampled signals may then be provided to signal separation stage 320for further signal isolation, although this is not required. Note thatsingle bidirectional coupler 510 allows for continuous communicationbetween the Ethernet 501 and 502 devices. Of course in this example andin the examples to follow, it also possible to reverse the polarity ofthe signals into the couplers such that the CF node couples out the Badata and the CR node couples out the Ab data.

Referring to FIG. 5B, an example dual bidirectional coupler 520 isdepicted as being coupled to a communication path with an Ethernetdevice 501 (A system) and an Ethernet device 502 (B system). Dualbidirectional coupler 520 may achieve better signal separation thansingle bidirectional coupler 510 of FIG. 3A. Dual bidirectional coupler520 includes a first bidirectional coupler stage 520A coupled to asecond bidirectional coupler stage 520B. Note that the use of first,second, and so on in the claims and in the specification is not meant toimply any type of ordering, but is only meant to distinguish onecomponent from another. As mentioned previously with respect to FIG. 5A,the Ethernet devices 501 and 502 communicate using a 100 ohmdifferential twisted pair cable, while dual bidirectional coupler 520 isconfigured for a single ended 50 ohm line. Accordingly, impendencematching circuits 515 and 516, which have the same functionality as thematching circuits of FIG. 5A, are implemented to allow for signaltransmission.

In operation, bidirectional coupler stage 520A is configured to couple asample of the A data out of the full-duplex bidirectional A+B data beingtransmitted. Since coupler stage 520A is a bidirectional coupler stage,coupler stage 520A includes a CF and a CR node. The CR node, however, istypically terminated in a 50 ohm termination as coupler stage 520A isconfigured to sample the forward A data and not the reverse B data.However, since the A+B data is bidirectional, coupler stage 520A may notbe able to fully isolate the B data and consequently may couple out asampled signal that is labeled as Ab data, which illustrates that thesignal mostly comprises A data, but may have some portion of B dataincluded. Note that bidirectional coupler stage 520A allows forcontinuous communication between the Ethernet 501 and 502 devices.

In like manner, bidirectional coupler stage 520B is configured to couplea sample of the B data out of the full duplex bidirectional A+B databeing transmitted. Since coupler stage 520B is a bidirectional couplerstage, coupler stage 520B also includes a CF and a CR node. The CR nodeis also typically terminated in a 50 ohm termination as coupler stage520B is configured to sample the forward B data and not the reverse Adata. However, since the A+B data is bidirectional, coupler stage 520Bmay not be able to fully isolate the A data and consequently may coupleout a sampled signal that is labeled as Ba data, which illustrates thatthe signal mostly comprises B data, but may have some portion of A dataincluded. Note that single bidirectional coupler stage 520B also allowsfor continuous communication between the Ethernet 501 and 502 devices.The sampled Ab and Ba data may then be provided to signal separationstage 320 for further separation if necessary.

Referring now to FIG. 5C, a differential bidirectional coupler 530 isdepicted as being coupled to the communication path with an Ethernetdevice 501 (A system) and an Ethernet device 502 (B system).Differential bidirectional coupler 530 may achieve better signalseparation than either of the couplers discussed in relation to FIGS. 5Aand 5B. Differential bidirectional coupler 530 includes a first couplerstage 530A and a second coupler stage 530B. Note that the configurationof coupler 530 allows for the direct coupling of the 100 ohmdifferential lines without the need for impedance matching circuits suchas circuits 515 and 516. As with the other coupler examples,differential bidirectional coupler 530 also allows for continuouscommunication between the Ethernet 501 and 502 devices.

In operation, coupler stage 530A is configured to couple a sample of theA data out of the full-duplex bidirectional A+B data being transmitted.Being bidirectional, coupler stage 530A includes a CR node that isterminated in a 50 Ohm termination, while the CF node couples out theforward Ab signal as described previously. In like manner, coupler stage530B couples a sample of the B data out of the A+B data beingtransmitted. Coupler stage 530B, also being bidirectional, includes a CRnode that is terminated in a 50 Ohm termination, while the CF nodecouples out the forward Ba signal as described previously. The Ab and Basignals may then be provided to signal separation stage 320 ifnecessary.

IV. Example Signal Separation Stage

As mentioned previously, signal separation stage 320 may be implementedin one or more components of the passive full-duplex bidirectional ZPLnetwork tap 300 or it may be a stand alone component of the ZPL tap 300.Signal separation stage 320 may include both hardware, whether discreteanalog or digital components, and software, or any combination ofhardware and software, that may be used to implement various methodsthat are configured to further separate the A component from the Absignal and the B component from the Ba signal.

In one embodiment, signal separation stage 320 may be implemented as aprogrammable attenuator and a differencing amplifier with gain that maybe part of signal separator 310 or stand alone components. In otherembodiments, signal separation stage 320 may be implemented as a DigitalSignal Processing (DSP) module that is included in both Phys 330 and340. In still other embodiments, the signal separation stage may beincluded as a module of processor 370. In further embodiments, thesignal separation module may be distributed across the signal separator310, the Phys 330 and/or 340, and the processor 370 or even othercomponents of the passive full-duplex bidirectional ZPL network tap 300.

Referring now to FIG. 9, FIG. 9 illustrates a method 900 for a signalseparation stage implemented in a signal separator 310, a DSP moduleimplemented in each one of Phys 330 and 340, or processor 370, eitherseparately or in combination, to separate a first and a second signalcomponent from a first data stream used in communication between twodevices. Note that although the method 900 will be described in relationto the environment of FIGS. 4 and 5, this is for illustration only andshould not be used to limit the scope of the appended claims. It isanticipated that method 900 may be practiced in numerous environments.

Method 900 includes obtaining or receiving 902 from the first datastream a second data stream comprising at least a portion of the firstcomponent and a portion of the second component that is smaller than thefirst component. For example, in one embodiment, signal separator 310may obtain a second data stream that includes the A data and a portionof B data that is smaller than the A data (e.g., signal Ab) aspreviously explained. In alternative embodiments, the second data streamincluding the A data and the portion of B data may be received by areceive module of processor 370 or of a DSP module of Phys 330 and 340.

Method 900 also includes obtaining or receiving 904 from the first datastream a third data stream comprising at least a portion of the secondcomponent and a portion of the first component that is smaller than thesecond component. For example, in one embodiment, signal separator 310may obtain a third data stream that includes the B data and a portion ofA data that is smaller than the B data (e.g., signal Ba) as previouslyexplained. In alternative embodiments, the third data stream includingthe B data and the portion of A data may be received by a receive moduleof processor 370 or of a DSP module of Phys 330 and 340.

Method 900 further includes determining 906 a reverse couplingcharacteristic. For example, a characterization module of the signalseparator 310, processor 370 or a DSP module of the Phys 330 and 340 maydetermine, based on the coupling characteristics of signal separator310, the reverse coupling characteristic. In other embodiments, areverse coupling characteristic that has been determined ahead of timemay be obtained by the characterization module. Note that for thepurposes of the embodiments disclosed herein, obtaining a predeterminedreverse coupling characteristic is considered to be a form ofdetermining the reverse coupling characteristic.

Method 900 additionally includes applying 908 the reverse couplingcharacteristic in an operation to remove at least a portion of thesecond component from the second data stream. For example, the signalseparator 310, processor 370 or a DSP module of the Phys 330 and 340 mayperform the operation, as will be explained in more detail to follow, toremove at least some of the B data from the second data stream, thusleaving substantially only the A data as part of the second data stream.

Method 900 finally includes applying 910 the reverse couplingcharacteristic in an operation to remove at least a portion of the firstcomponent from the third data stream. For example, the signal separator310, processor 370 or a DSP module of the Phys 330 and 340 may performthe operation, as will be explained in more detail to follow, to removeat least some of the A data from the third data stream, thus leavingsubstantially only the B data as part of the third data stream.

FIG. 10 illustrates an environment and process flow 1000 that may beimplemented to perform an operation to extract the B data from a datastream comprising B data and a portion of A data that is less than the Bdata or the A data from a data stream comprising A data and a portion ofB data that is less than the A data. Note that the modules andcomponents of environment 1000 may be included as part of signalseparator 310, processor 370, a DSP module of Phys 330 and 340, or someother component of passive full-duplex bidirectional ZPL network tap300. Alternatively, the modules and components of environment 1000 maybe disturbed across one or more of the signal separator 310, processor370, a DSP module of Phys 330 and 340, or some other component ofpassive full-duplex bidirectional ZPL network tap 300. Note that themodules and components of environment 1000 may be implemented ashardware, software, or any combination of the two without restriction ascircumstances may warrant.

For example, a receive module 1010 may receive a data stream 1001 thatcomprises B data and a portion of A data that is smaller than the Bdata. This is denoted as Ba data. In addition, the receive module 1010may also receive a data stream 1005 that comprises A data and a portionof B data that is smaller that the A data and is denoted as Ab data.Note that the data streams 1001 and 1005 may be received from the signalseparating portions of signal separator 310.

The environment 1000 may include a characterization module 1020.Characterization module is configured to determine or alternatively toreceive from another source, the reverse coupling characteristic 1025for the signal separator 310. The reverse coupling characteristic isdenoted as a factor γ.

The data stream 1005 and the reverse coupling characteristic 1030 maythen be received by a multiply module 1030. The multiply module isconfigured to multiply data stream 1030 and reverse couplingcharacteristic to produce a signal 1035.

An add/subtract module 1040 then subtracts the signal 1035 from the datastream 1001. The difference is then provided to multiply module 1030,where the difference is multiplied by 1/(1−γ²). The resultant separatedsignal 1050 will be comprised substantially of B data and no A data. TheA data can be extracted by using this same method.

In mathematical terms, the process flow of environment 1000 isillustrated below. Note that equations 1 and 2 are derived directly fromthe process flow of environment 1000. Equations 3 and 4 are based on thefact that the a data and b data are equal to the reverse couplingcharacteristic times the A data and B data respectively.A=(Ab−γBa)/(1−γ²)  (Equation 1)B=(Ba−γAb)/(1−γ²)  (Equation 2)For example, to extract Ba=γA  (Equation 3)b=γB  (Equation 4)Ba=B+a=B+γA  (Equation 5)Ab=A+b=A+γB  (Equation 6)Substituting:B=(B+γA−γ(A+γB))/(1−γ²)B=(B+γA−γA−γ ² B)/(1−γ²)B=(B−γ ² B)/(1−γ²)B=B(1−γ²)/(1−γ²)B=B

Note that method and process flow shown in relation to environment 1000is only one of many possible signal separation operations and should notbe used to limit the scope of the invention.

In some embodiments, signal separation stage 320 can achieve at least80% separation of the signals. For example, if the signal separationstage 320 were separating out the Ab signal, then 80% of the resultingsignal would be A data and 20% would be b data. In other embodiments,signal separation stage 320 may achieve 90% separation of signals. The80% and 90% examples are meant to be typical examples with otherpercentages contemplated so as to enable the Phys to receive theseparated signals in as pure a form as possible.

Referring now to FIGS. 6A-6D, examples of actual signal separationachievable by signal separator 310 by itself or in combination withsignal separation stage 320 is illustrated. These figures illustrateactual results as measured on various test equipment.

FIG. 6A includes a signal 601 which illustrates the A+B data of FIG. 4.Signal 601 includes an A data portion 601 a and a B data portion 601 b.FIG. 6A further illustrates the results of subjecting signal 601 topassive full-duplex bidirectional ZPL network tap 300, specificallysignal separator 310 by itself or in combination with signal separationstage 320. The resultant signal is designated as 602. As illustrated,signal 602 includes an A data portion 602 a that is substantiallysimilar to an inverted A data portion 601 a. The B data portion 602 b,however, has substantially been removed from signal 602. Accordingly,passive fall-duplex bidirectional ZPL network 300 is shown to achieve ahigh level of success in separating the B data from the A data.

In like manner, FIG. 6B also includes a signal 610 that illustrates theA+B data of FIG. 4. Signal 610 includes an A data portion 610 a and a Bdata portion 610 b. FIG. 6B further illustrates the results ofsubjecting signal 610 to the passive full-duplex bidirectional ZPLnetwork tap 300, specifically signal separator 310 by itself or incombination with signal separation stage 320. The resultant signal isdesignated as 611. As illustrated, signal 611 includes an A data portion611 a that is substantially similar to an inverted A data portion 610 a.The B data portion 611 b, however, has substantially been removed fromsignal 611. Accordingly, passive full-duplex bidirectional ZPL network300 is once again shown to achieve a high level of success in separatingthe B data from the A data.

FIG. 6C illustrates in further detail the signal separation that may beachieved by passive full-duplex bidirectional ZPL network tap 300. Forexample, FIG. 6C illustrates a signal 620 which may correspond to thefull-duplex bidirectional A+B data of FIG. 4. As such, signal 620includes both an A data and B data portions. FIG. 6C further illustratesthe results of subjecting signal 620 to passive full-duplexbidirectional ZPL network tap 300, specifically signal separator 310 byitself or in combination with signal separation stage 320. These resultsare designated as signals 621 and 622.

For example, signal 621 illustrates an A data portion that issubstantially similar to the A data portion of signal 620 while having aB data portion that has been substantially removed. In like manner,signal 622 includes a B portion that is substantially similar to the Bdata portion of signal 620 while having an A data portion that has beensubstantially removed. Finally, FIG. 6C includes a signal 623 that isthe combination of signals 621 and 622. Signal 623 illustrates thatcombining the two signals that have been subjected to signal separation(e.g., signals 621 and 622) produces a signal that is substantiallysimilar to signal 620.

In similar manner, FIG. 6D illustrates in further detail the signalseparation that may be achieved by passive fall-duplex bidirectional ZPLnetwork tap 300. For example, FIG. 6D also illustrates a signal 630which may correspond to the full-duplex bidirectional A+B data of FIG.4. As such, signal 630 includes both an A data and B data portions. FIG.6D further illustrates the results of subjecting signal 630 to passivefull-duplex bidirectional ZPL network tap 300, specifically signalseparator 310 by itself or in combination with signal separation stage320. These results are designated as signals 631 and 632.

For example, signal 631 illustrates an A data portion that issubstantially similar to the A data portion of signal 630 while having aB data portion that has been substantially removed. In like manner,signal 632 includes a B portion that is substantially similar to the Bdata portion of signal 630 while having an A data portion that has beensubstantially removed. Finally, FIG. 6D also includes a signal 633 thatis the combination of signals 631 and 632 and that produces a signalthat is substantially similar to signal 630.

V. Example Phys

As previously mentioned, passive full-duplex bidirectional ZPL networktap 300 also includes Phys 330-360. In one embodiment, the Phy IC chipsmay be configured in a quad configuration included on a single chip asillustrated at 331 in FIG. 4. The quad Phy 331 may consist of the fourPhys 330-360. In other embodiments, the Phys 330-360 may be individual,separate IC chips. In still other embodiments, the Phy IC chips may beimplemented as any combination of two of the Phys, for example Phys 330and 350 on an IC chip and Phys 340 and 360 on an IC chip. In someembodiments, Phy 330 and 340 may have a connection 332 that allows thechips to communicate with each other when implemented as separate chips.Note that the exact implementation of the Phy chips 330-360 (e.g., as aquad chip, separate, individual chips, or any combination of two of thePhys) is not important to the principles of the present invention.Further note that the actual implementation of the internal circuitryand internal operations of the Phy ICs is unimportant to the principlesof the present invention. Rather, it is the terminal characteristics ofthe Phy ICs, especially a unidirectional or listen only terminalcharacteristic, that are important to the principles of the presentinvention, as will be explained in more detail to follow.

The Phys, whether implemented as a quad Phy IC 331 chip or individualPhy IC chips 330-360, are configured to have specific terminalcharacteristics. For example, Phy IC chips 330 and 340 are configured tobe receive or listen only Phys. This means that Phys 330 and 340,regardless of how implemented (e.g., as part of a quad chip, separate,individual chips, or any combination of two of the Phys), have frontends that are different from the prior art Phys previously described inthat Phys 330 and 340 have front ends that do not transmit. For example,Phys 330 and 340 ignore any auto negotiations between Ethernet or otherprotocol implanting devices A and B that are coupled to passivefull-duplex bidirectional ZPL network tap 300 and therefore do not needto undergo any training by the devices before the Phy IC chips can lockonto and monitor the signals between devices A and B. Instead, the Phys330 and 340 monitor the full-duplex bidirectional communication betweendevices A and B until a data unit such as a header or idle isrecognized, at which time the Phys 330 and 340 lock onto the monitoredsignal. Both Phy IC chips operate as slave only chips that use thereceived signal clock and have no echo canceling.

Phys 330 and 340 can be power cycled on and off without networkcommunication being effected and both can monitor the conversationbetween devices A and B at any time. In other words, the listen onlyPhys 330 and 340 may lock onto the communication signals between devicesA and B without any external help from the network devices. Accordingly,Phys 330 and 340 are configured as unidirectional receive only Phy ICs.In some embodiments, as mentioned previously, one or more of the Phy ICsmay include digital signal processing that may assist in further signalseparation or, as mentioned previously, may act as the signal separationstage 320.

Operation of the unidirectional receive only Phys 330 and 340 will nowbe described. As illustrated in FIG. 4, Phy 330 receives the recovered Adata and what portion of B data remains from the signal separation stage320 and/or the signal separator 310. Phy 330 then provides the signal toPhy 350, which in turn provides the signal to a monitoring device Athrough tap port 304 a. In like manner, Phy 340 receives the recovered Bdata and what portion of A data remains from the signal separation stage320 and/or the signal separator 310. Phy 340 then provides the signal toPhy 360, which in turn provides the signal to a monitoring device Bthrough tap port 304 b.

As mentioned above, the Phys 330 and 340 are configured in a novel waydifferent from conventional Phys to have front end terminalcharacteristics that make them listen only or receive only Phys. FIG. 11illustrates a method 1100 for configuring and using a listen only orreceive only Phy according to the principles of the present invention.Such a method was successfully performed using the DP83865 10/100/1000Ethernet Physical Layer chip available from National SemiconductorCorporation doing business at 2900 Semiconductor Drive, Santa Clara,Calif. 95052-8090. Note however, that method 1100 is not limited to theuse of the DP83865 chip.

Method 1100 includes obtaining 1102 a Phy 330 or 340 with a front endthat does not have transmit functionality. For example, in someembodiments, a Phy 330 or 340 implemented using the DP83865 10/100/1000Ethernet Physical Layer chip available from National SemiconductorCorporation may have its front end transmit functionality disabled byobtaining a firmware patch configured to disable the transmitfunctionality. For instance, one or more registers of the DP83865 mayhave code or firmware modified or newly written to it that disables thetransmit functionality. The function of this firmware is to place theDP83865 into a forced mode of operation (using the DP83865 special“manual” configuration mode). For example, the code or firmware maydisable 1000BASET Auto-Negotiation, disable one or more output driversand configure the DP83865 as a slave device.

In other embodiments, a Phy chip may be obtained that has previously hadits front end transmit functionality disabled or removed by hard codingat manufacture time or by other process now known in the art orhereafter developed. The embodiments disclosed herein contemplate otherways of obtaining a Phy chip with no front end transmit functionality.

Method 1100 also includes viewing or monitoring 1104 incoming dataframes or packets with the Phy chip. For example, the Phy 330 or 340that has no front end transmit functionality may receive the separated Aor B data from signal separation stage 320 and/or signal separator 310.The Phy 330 or 340 may then view the A or B data.

Method 1110 also includes recognizing 1106 known signal elements withthe Phy chip. For example, by knowing that the type of data to lockonto, such as Gigabit Ethernet data, the clock rate is defined, so thatperforming clock recovery from the receive data stream is possible.Further, it well known that Ethernet data has a known signal packet withknown elements such as three idles between data frames. In oneembodiment, the PCS (Physical Coding Sublayer) of Phy chip 330 or 340implemented as the DP83865 chip is configured to view the data steamuntil it recognizes the Ethernet idle or some other known element. Inthis way, the Phy chip is able to learn that the received data is anEthernet signal without having to undergo auto negotiation and to lockonto this signal.

Method 1100 further includes using 1108 the known signal element to atleast partially lock onto the data frame or packet. For example, Phy 330or 340 uses the known signal element such as the Ethernet idle to lockonto the A data stream or the B data stream. The data stream may then beprovided by Phys 330 and 340 to Phys 350 and 360, which in turn mayprovide the signals to external monitoring devices through tap ports 304a and 304 b. Note that the amount of time it takes for Phy 330 or 340 tolock onto the signal is not important. As passive full-duplexbidirectional ZPL network tap 300 is a passive tap, the speed that Phys330 and 340 lock onto the signal does not effect the operation of theZPL tap 300. Advantageously, users of network devices A and B do notnotice when the listen only Phys 330 and 340 lock onto the data stream.Further, power may be cycled on and off to the listen only Phys withoutusers of network devices A and B knowing and without any data beinglost.

VI. Example Methods and Systems

As described herein, the systems of the invention can be used to tap anetwork cable and access network data. The invention further extends tothe use of the systems described herein to access network data, tosupply the network data to any associated device, and to process thedata. For instance, the passive full-duplex bidirectional ZPL networktap 300 can be used to access Ethernet data being communicated over acopper network cable and to supply the accessed data to a networkanalyzer device. The network analyzer device can then perform diagnosticfunctions on the accessed data.

The network analyzer can be a local device that is dedicated for usewith a single passive full-duplex bidirectional ZPL network tap 300.Alternately, the network analyzer can be used in conjunction with aplurality of passive full-duplex bidirectional ZPL network taps 300 aswill be described below, and can access and analyze or otherwise processthe data accessed by any of the associated passive full-duplexbidirectional ZPL network taps 300. The network analyzer can instead beremote and receive the accessed data through a data network.

The data can also be used for any other purpose. For example, the datacan be stored and analyzed or processed in a delayed manner.Alternately, the access data can be processed in real time. Theinvention extends to methods for using the systems described herein toaccess Ethernet data and to analyze the content, such as the content ofdata files, telephone conversations carried using Voice over IP (VoIP)or other protocols, images, video, audio, or other data types. It isnoted that one of the benefits of the passive full-duplex bidirectionalZPL network taps of the invention is that they are passive and do notaffect the data being transmitted over the network except for someslight attenuation thereof. Unlike conventional taps, which use relayswith physical switches, the passive full-duplex bidirectional ZPLnetwork taps of the invention do not include any active componentspositioned in-line with the network cable that could cause data packetloss or otherwise cause users on either end of the network link to beaware of the fact that data is being accessed by a tap. Regardless ofloss of power to the tap, there is no loss of communication between theEthernet devices. This feature is particularly useful for governmentalagencies or other entities that are authorized to access network datafor the purposes of monitoring and surveillance of communications.

Reference is now made to FIG. 7. As mentioned, depending upon the needsof the user, the passive full-duplex bidirectional ZPL network tap 300can be employed alone or, as discussed above in connection with FIG. 2,as part of a larger group of ZPL tap devices. In the event that multiplepassive full-duplex bidirectional ZPL network tap devices are employed,those devices are fitted in the chassis 252, which is suitably sized andconfigured to retain a predetermined number of devices therein. In theexample arrangement shown in FIG. 7, twenty four (24) passivefull-duplex bidirectional ZPL network tap devices 300 are retained inthe chassis 252 of the tap array 250, arranged in two (2) rows of twelve(12) cards each. When thus arranged, the 24 passive full-duplexbidirectional ZPL network tap devices 300 collectively define a chassisform factor having approximate dimensions of about 17″ (1U) wide byabout 7″ (4U) high by about 8″ deep. So configured, the ZPL tap array250 can tap data streams from a variety of points in the computernetwork 100 and forward these streams to respective monitoring devicesfor analysis or other treatment.

Reference is now made to FIG. 8. In another example embodiment of thepresent invention, the network tapping functions of one or more passivefull-duplex bidirectional ZPL network taps can be merged with dataaggregating functionality provided by an aggregator to enable both datatapping and aggregating in an integrated device. One example of such adevice is shown in FIG. 8, which shows a ZPL tap/aggregator (“ZPL T/A”),generally designated at 400. As shown, the ZPL T/A 400 includes asub-chassis 402 that houses various components, including a plurality ofpassive full-duplex bidirectional ZPL network tap devices in the form oftap data cards 404, and an aggregator card 406. The ZPL T/A 400generally functions by tapping data from various points on the networkusing the plurality of passive full-duplex bidirectional ZPL network tapdata cards 404, then aggregating that data via the aggregator card 406before the data is forward to a monitoring device or other suitablecomponent. Use of the ZPL T/A 400 in this manner simplifies the tappingprocess and topology by integrating various functionalities into onedevice.

In a general sense, the ZPL T/A includes within its sub-chassis anumber, “X,” of ZPL active plug-in data cards that operably connect withthe corresponding X-into-1 aggregator plug-in card, where “X” againrepresents the number of cards in the group of ZPL active data cards. Assuch, it is appreciated that the number of passive full-duplexbidirectional ZPL network tap data cards that are to be connected to ais corresponding aggregator card can be varied. In the exampleembodiment illustrated in FIG. 8, five (5) tap data cards are connectedwith a corresponding 5-into-1 aggregator card. This combinationtherefore provides both passive fall-duplex bidirectional ZPL networkaggregation and passive full-duplex bidirectional ZPL network TAPcapabilities. In other embodiments, multiple passive full-duplexbidirectional ZPL network tap data cards could be included with multipleaggregator cards within a single sub-chassis, wherein some of the tapdata cards are assigned to one aggregator and the remaining tap datacards are assigned to the other aggregator card.

In the present embodiment, both the passive full-duplex bidirectionalpassive full-duplex bidirectional ZPL network tap data cards 404 and theaggregator card 406 have the same form factor. One example form factorfor the aforementioned cards is about ⅞ inches wide by 3.5 inches (2U)high by 5.5 inches deep. Of course, other form factors may be definedand employed as well, and the scope of the invention is not limited toany particular form factor or card configuration.

In greater detail, each of the passive full-duplex bidirectional ZPLnetwork tap data cards 404 and aggregator card 406 includes a housingincluding a housing front face 408. An LED bank 410, including LEDs 410a and b, are included on the front face 408 of each passive full-duplexbidirectional ZPL network tap data card 404 of the ZPL T/A 400.Similarly, the front face 408 of the aggregator card 406 includes an LEDbank 411 including LEDs 411 a, b, and c. The LED banks 410 and 411 areemployed to enable the functionality status of the passive full-duplexbidirectional ZPL network tap data cards 404 and aggregator card 406 tobe determined.

Also included on the front faces of 408 of the tap data cards 404 andaggregator card 406 are a plurality of interfaces, or ports, forinterfacing with the communications network. In particular, each passivefull-duplex bidirectional ZPL network tap data card 404 includes twoRJ-45 network ports 412 a and 412 b on the front face 408, and a dualoutput backplane connector (not shown) on the rear portion of the card.In an alternative embodiment the rear portion of the card can includetwo RJ-45 outlet ports. Correspondingly, the aggregator card 406includes RJ-45 tap ports 414 a and 414 b on its front face and abackplane connector (not shown) on the rear portion of the card. Notethat this combination of interfaces is merely shown as an example, andadditional or alternative interfaces may be employed.

The functionality of each passive full-duplex bidirectional ZPL networktap data card 404 is similar to that of the passive full-duplexbidirectional ZPL network tap 300 described above in connection withFIGS. 3 and 4. As such, the network ports 412 a, b of each tap data card404 are operably connected to a node on the communications network bycommunication cables such that data traversing the network at the nodecan be input into and output from the tap data card via the networkports. Each passive full-duplex bidirectional ZPL network tap data card404 can be interconnected with a different node on the network so as toenable data from various points on the network to be tapped.

The backplane connector on the rear portion of each passive full-duplexbidirectional ZPL network tap data card 404 is operably connected to thebackplane connector of the aggregator card 406 so as to enable each datastream from each outlet port to be input into the aggregator card. Thus,in the ZPL T/A configuration shown in FIG. 8, the aggregator card 406 isconfigured to receive data streams from the outlet ports of each of thepassive full-duplex bidirectional ZPL network tap data cards 404 via itsbackplane connector.

Once received by the aggregator card 406, the data streams received fromeach tap data card outlet port are combined, or aggregated, into twocomposite data streams that are directed out of the aggregator card 406via the tap ports 414 a, b. These data streams can then be forwarded viacommunication cables to a monitoring device or other suitable location.

As indicated in FIG. 8, each of the passive full-duplex bidirectionalZPL network tap data cards 404 of the ZPL T/A 400 includes the LED bank410, including the LEDS 410 a and b. Each of the LEDs 410 a and b canact as a status indicator, such as a bi-color LED for example, in orderto supply a visual status indication with regard to the linkconnectivity for those cards. The LEDs 410 a, b can be used to indicatethe link status of each of the passive full-duplex bidirectional ZPLnetwork tap data cards 404. In one embodiment, the LED 410 a will lightgreen when the listen only Phy 330 is detecting valid data on networkport A, while the LED 410 b will light green listen only Phy 340 isdetecting valid data on network port B. In addition, the front face 408of each passive full-duplex bidirectional ZPL network tap data card 404may include further identifications for each of the network ports 412 aand 412 b. Note that the labeling present on the front face 408 of thepassive full-duplex bidirectional ZPL network tap data cards 404 can bemodified according to the different configurations possible with the tapdata cards or the aggregator card.

Similar to the passive full-duplex bidirectional ZPL network tap datacard 404, the aggregator card 406 also includes indication functionalitythat enables a user to make various determinations concerning theoperation and status of the card. As mentioned, the example embodimentdisclosed in FIG. 4 includes an aggregator card having the LED bank 411including the LEDs 411 a, b, and c. The LED 411 c lights green when DCpower is detected on the DC power port, and lights red or isextinguished, when no DC power is detected on the DC power port. Similarto the tap data cards 404, the LEDs 411 a, b of the aggregator card 406can be used to indicate the link status of the aggregator ports: in oneembodiment, the LED 410 a will light green if a valid Gigabit Ethernetconnection is detected on network port A, while the LED 410 b will lightgreen if a valid Gigabit Ethernet connection is detected on network portB.

Together with FIG. 8, reference is now made to FIG. 12. As previouslymentioned, the components of the ZPL T/A 400 are included in a housingreferred to herein as the sub-chassis 402. In general, the form factorof a particular sub-chassis will depend upon the number of cards thatare included in the sub-chassis. As an example, the 5-into-1tap/aggregator arrangement disclosed in FIG. 9 has a form factor of lessthan about 7″ high by about 5⅔″ wide by about 12″ deep.

As suggested above, however, multiple sub-chassis can be combinedtogether in an equipment rack to form or define a chassis, such as thechassis shown in FIG. 9 and generally designated at 450. In the presentexample embodiment, five sub-chassis 402, each including five passivefull-duplex bidirectional ZPL network tap data cards 404 and oneaggregator card 406, are combined together in an equipment rack to formthe chassis 450 that can provide ZPL data tapping and aggregation forthirty (30) data links. The form factor for the example arrangement ofthe chassis 450 in FIG. 6 is about 7″ high by about 19″ wide by about12″ deep. This arrangement generally corresponds with a standard 4U rackmount.

In the example arrangement illustrated in FIG. 12, one of thesub-chassis 402 includes an unutilized link 452, while the chassis 450itself includes a vacant sub-chassis location 454. These detailsillustrate that fewer than all of the links in any given a sub-chassis,and fewer than all sub-chassis locations may be employed in a particularconfiguration. Because some or all of the links of any number ofsub-chassis can be employed, embodiments of the invention enablevirtually unlimited flexibility in terms of the definition andimplementation of ZPL tap/aggregation arrangements. Moreover, becausedata signal transfer between the pluggable cards of the chassis occursin the chassis backplane, the need to use cables and other connectors inone embodiment is greatly reduced.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A passive full-duplex bidirectional zero packet loss (ZPL) networktap comprising: first and second network ports configured to operablyconnect with first communication cables, the first communication cablesconfigured to carry full-duplex bidirectional data signals comprisingfirst and second data components to and from the network tap device; afirst tap port configured to operably connect with second communicationcables; a signal separator configured to have a first node operablyconnected to the first network port and a second node operably connectedto the second network port, wherein the signal separator is configuredto pass through the full-duplex bidirectional data signals from thefirst network port to the second network port and from the secondnetwork to the first network port, and wherein the signal separator isfurther configured to obtain a first signal portion comprising at leastthe first data component; a first digital signal processing (DSP) stageconfigured to be operably connected to the signal separator, wherein thefirst DSP stage is configured to receive the first signal portion,wherein the first DSP stage is further configured to substantiallyremove at least a portion of any second data component included in thefirst signal portion; a first receive only physical interface device(Phy) configured to be operably connected to the first DSP stage and tothe first tap port so as to receive the first signal portion from thefirst DSP stage and provide the first signal portion to the first tapport.
 2. The passive full-duplex bidirectional ZPL network tap inaccordance with claim 1, further comprising: a second tap portconfigured to operably connect with the second communication cables; asecond DSP stage operably connected to the signal separator; wherein thesignal separator is further configured to obtain a second signal portioncomprising at least the second data component and the second DSP stageis configured to receive the second signal portion, wherein the secondDSP stage is further configured to substantially remove at least aportion of any first data component included in the second signalportion; and a second receive only physical interface device (Phy)configured to be operably connected to the second DSP stage and to thesecond tap port so as to receive the second signal portion from thesecond DSP stage and provide the second signal portion to the second tapport.
 3. The passive full-duplex bidirectional ZPL network tap inaccordance with claim 2 further comprising: a first transmit and receivePhy configured to be operably connected to the first receive only Phy soas to receive the first signal portion from the first receive only Phyand provide the first signal portion to the first tap port; and a secondtransmit and receive Phy configured to be operably connected to thesecond receive only Phy so as to receive the second signal portion fromthe second receive only Phy and provide the second signal portion to thesecond tap port.
 4. The passive full-duplex bidirectional ZPL networktap in accordance with claim 2, wherein the first and second listen onlyPhys are configured to ignore auto negotiation between first and seconddevices of a communications network and to lock onto the data signalswithout any external help from the first and second devices of thecommunications network.
 5. The passive full-duplex bidirectional ZPLnetwork tap in accordance with claim 2, wherein the first and second tapports are configured to be connected via the second communication cablesto at least one monitoring device for monitoring the first and seconddata portions.
 6. The passive full-duplex bidirectional ZPL network tapin accordance with claim 1, wherein the signal separator is abidirectional coupler.
 7. The passive full-duplex bidirectional ZPLnetwork tap in accordance with claim 1, wherein the passive full-duplexbidirectional ZPL network tap does not affect data being transmittedover a communications network except for normal attenuation.
 8. Thepassive full-duplex bidirectional ZPL network tap in accordance withclaim 1, wherein communication between first and second devices of acommunications network is not lost due to a loss of power or other faultto the passive full- duplex bidirectional ZPL network tap.
 9. Thepassive full-duplex bidirectional ZPL network tap in accordance withclaim 1, wherein the passive full-duplex bidirectional ZPL network tapis configured to monitor and analyze the content of data files,telephone conversations carried using Voice over IP (VoIP) or otherprotocols, images, video, audio, or other data types.
 10. The passivefull-duplex bidirectional ZPL network tap in accordance with claim 1,wherein the passive full-duplex bidirectional ZPL network tap isconfigured for use in a copper Gigabit Ethernet communications network.11. In one or more Digital Signal Processing (DSP) stages coupled to thecommunication path of a first and second Ethernet device, the first andsecond Ethernet devices communicating by use of a full-duplexbidirectional first data stream including a first and a second datacomponent, a method for the one or more DSP stages to separate the firstand second components, the method comprising: receiving from the firstdata stream a second data stream comprising a portion of the first datacomponent and a portion of the second data component that is less thanthe first data component; determining a reverse coupling characteristicof a signal separator operably connected to the DSP stage; and applyingthe reverse coupling characteristic in an operation to remove at least aportion of the second data component from the second data stream whileleaving the first data component.
 12. The method in accordance withclaim 11 further comprising: receiving from the first data stream athird data stream comprising a portion of the second data component anda portion of the first data component that is less than the second datacomponent; and applying the reverse coupling characteristic in anoperation to remove at least a portion of the first data component fromthe third data stream while leaving the second data component.
 13. Themethod in accordance with claim 12, wherein the second and third datastreams are received by a receive module of the DSP stage.
 14. Themethod in accordance with claim 12, wherein the reverse couplingcharacteristic is determined by a characterization module or wherein thecharacterization module is configured to receive a couplingcharacteristic that was previously determined.
 15. The method inaccordance with claim 12, wherein the operation to remove the portion ofthe second data component from the second data stream or the operationto remove a portion of the first data component from the third datastream is performed at least partially by an add/subtract module and amultiplication module of the DSP stage.
 16. The method in accordancewith claim 12, wherein DSP stage is part of a passive full-duplexbidirectional ZPL network tap device.
 17. A passive full-duplexbidirectional zero packet loss (ZPL) network tap comprising: a multiplymodule having one or more input nodes and one or more output nodes,wherein the multiply module is configured to multiply data valuesprovided to the one or more input nodes and to provide the resultingproduct of the multiplied data values at the one or more output nodes;an add/subtract module having one or more input nodes and one or moreoutput nodes, wherein the add/subtract module is configured to add orsubtract data values provided to the one or more input nodes and toprovide the resulting sum or difference of the added or subtracted datavalues at the one or more output nodes; a receive module configured toreceive a first data stream comprising a first data value and a seconddata value that is less than the first data value and a second datastream comprising the second data value and the first data value that isless than the second data value; a characterization module configured toobtain a characterization value of the passive full-duplex bidirectionalZPL network tap; and one or more processors or one or more DigitalSignal Processors (DSP) configured to execute one or more instructionsthat cause the passive full-duplex bidirectional ZPL network tap tosubstantially remove the second data value from the first data stream orto substantially remove the first data value from the second datastream.
 18. The passive full-duplex bidirectional ZPL network tap inaccordance with claim 17, wherein the instructions comprise thefollowing: a first multiplication instruction to multiply thecharacterization value and the first data stream or the second datastream using the multiplication module to produce a first product; asubtraction instruction to subtract the first product from the seconddata stream or to subtract the first product from the first data streamusing the add/subtract module to produce a first difference; and asecond multiplication instruction to multiply the first difference witha value comprising 1/(1−the characterization value.sup.2) using themultiplication module.
 19. The passive full-duplex bidirectional ZPLnetwork tap in accordance with claim 17, wherein having the processorsor Digital Signal Processors execute the instructions results in thesecond data value being substantially removed from the first data streamor wherein having the processors or Digital Signal Processors executethe instructions results in the first data value being substantiallyremoved from the second data stream.
 20. The passive full-duplexbidirectional ZPL network tap in accordance with claim 17, wherein 80%or 90% of the first data value is removed from the second data streamand/or wherein 80% or 90% of the second data value is removed from thefirst data stream.